Reviewed arrays and linked lists. Discussed array and linked-list
implementation of stacks by describing the behavior of a stack and
asking them to define push and pop. Mixed success, but seemed like a
good exercise. Next up: queues, deques, and sequences.

– CS139.3: Told the class what was going to happen. Had a fruitful

review session of the past five problems. Made sure everyone knew
how to read input. Promised to discuss Arbitrage and Kissing Cousins
on Wednesday. Okay class session, although small.